Radiant heating systems include a central heater that is thermally coupled to radiators distributed in different zones of a building. In a conventional radiant heating system, radiators are positioned in different rooms in a residential structure and are operatively coupled to a central boiler. Hot water from the boiler is fed to the radiators to radiantly heat the respective rooms. In a zoned radiant heating system, each radiator is operatively connected to a respective thermostatic valve that opens and closes to control the flow of hot water into the radiator based on the environmental temperature in the respective zone. Traditional thermostatic valves comprise wax motors that open and close due to thermal expansion of a wax material driven by changes in environmental temperature. No other power source is required to open and close the valve. However, because conventional wax valves are only passively responsive to changes in environmental temperature, they are not suitable for centralized system control.
To provide some degree of centralized control to a zoned radiant heating system, electronic thermostatic radiator valves are used instead of wax motors. Unlike wax motors, electronic thermostatic radiator valves have valve positioners that must be powered to open and close the valve. But the thermostatic radiator valves are capable of communicating with a system controller that can control all of the valves to implement a coordinated control scheme to achieve the desired objectives for the system.